1. Field of the Invention
The present invention relates generally to radio frequency identification (RFID) devices and, more particularly, to the encapsulation and mounting of RFID devices. Specifically, the present invention relates to the domed encapsulation of RFID transponders and their mounting on surfaces that impede radio frequency (RF) transmissions.
2. Description of Related Art
Radio frequency identification (RFID) is an information acquisition technology. RFID systems are generally designed to manage assets of many types. RFID systems are generally comprised of transponders (a/k/a “tags”), a transmitter to provide energy to the tags, a receiver to receive transmissions from the transponders, and a computer system to process the received information. The transmitter and receiver may be combined into a single device often referred to as an interrogator or reader. Typically a small RFID tag is attached to the asset so that either the asset's presence at a certain location can be detected or the asset can be identified by the response of the tag to the interrogation either by hand-held interrogators or fixed-site interrogators that are encountered in the course of asset movement. The failure to detect an expected RFID signal may also be used as an indicator.
RFID transponders may be exposed to a variety of harsh environments during the course of their use. For this reason, tags must be tolerant of many hostile chemicals, abrasives, weather conditions and mechanical stresses. Although RFID devices generally are packaged in a plastic housing, these housings may lack sufficient properties to withstand harsh environments for prolonged periods.
Encapsulation of art images and advertising materials is a well-known process in the formation of domed labels. A process known as “domed encapsulation” provides an encapsulating material over a substrate on which artwork or advertising is placed. Generally, the encapsulating material is translucent, though in some instances it may be colored, tinted, or otherwise opaque. The encapsulating material makes the underlying art or advertisement stand out with a three-dimensional “wet” look and protects the artwork. Generally, the encapsulating material is comprised of an epoxy for an application where flexibility is not a requirement, or polyurethane where more flexibility is needed. Generally, the doming process depends on surface tension to form a bubble of the encapsulating material on an item being decorated without going off the edge of the item. The encapsulating material is applied to the substrate and, if required, then exposed to a hardening or curing process, such as exposure to ultra-violet light or heat. Known uses of the encapsulating process are the creation of identification, advertising and artwork used on automobiles, computers and computer cases, name badges and lapel pins.
RFID devices are commonly used on or near a number of surface materials. Some of these surfaces that are comprised of materials such as, for example, various metals, impede or block the transmission and reception of radio frequency (RF) signals by the RFID devices. In other instances, materials proximate to the surface on which the RFID device is mounted may impede the transmission and reception of RF signals by the RFID device. An example would be a glass or plastic container holding a fluid that interferes with the transmission and reception of RF signals by an RFID device mounted on or within the container.
Therefore, a method and apparatus are needed to overcome challenges associated with the use of RFID devices, some of which are given above, including protecting RFID devices through encapsulation, overlaying the devices with images, and mounting the devices so that their reception and transmission of RF signals is not impeded.